Cannot redeclare class in Symfony2 Twig extension - symfony

Question

I'm creating a Twig extension and activating it with a service. Everything works great except I'm trying to simply use another class from my Twig extension.
The idea is to instantiate the new class then use it as needed. Instantiating is a problem as it errors with:
Error: Cannot redeclare class NewClass in .../Bundle/NewClass.php line 13
Surely it instantiates it once. Why is this happening?
namespace Bundle\Twig;
use Bundle\NewClass;
class NewExtension extends \Twig_Extension
{
private $request;
private $new_class;
public function __construct($container) {
//get the Request object
$this->request = $container->get('request');
//instantiate new class
$this->new_class = new NewClass(); // this part triggers the error
}
///etc.

Answer 1

You should make your NewClass into a service and then inject that and the #request service into your twig extension rather than the container. Injecting the container directly is a bad idea apparently.
For example in your services..
services:
# create new class as a instantiated service
acme_demo.new_class:
class: Acme\DemoBundle\NewClass
arguments: [ '#request' ]
acme_demo.twig.acme_extension:
class: Acme\DemoBundle\Twig\AcmeExtension
arguments: [ '#request', '#acme_demo.new_class' ]
# inject the Request service and your class from above
tags:
- { name: twig.extension }
And then in your Twig extension
namespace Bundle\Twig;
use Bundle\NewClass;
class NewExtension extends \Twig_Extension
{
private $new_class;
public function __construct(NewClass $newClass) {
$this->new_class = $newClass;
}
///etc.
In your NewClass:
namespace Bundle;
class NewClass
{
private $param1;
private $param2;
public function __construct(Request $request)
{
$this->param1 = $request->get('param1');
$this->param2 = $request->get('param2');
// You could also add some check in here to make sure they are valid.
}